Shorting plug for diplex transmission lines



NW. 28, 194% G. A. KUMPF SHORTlNG PLUG FOR DIPLEX TRANSMISSION LINESFiled Feb. 27, 1948 INVENTOR E EDREEZ A. KUMPF ATTNY Patented Nov. 28,1959 SHGRTING PLUG FOR DKPLEX TRANS- MISSION LINES George A. Kumpf,Eriton, N. 3., assignor to Radio Corporation of America, a corporationct Delaware Application February 2'7, 19.48, Serial No. 11,503

Claims.

This invention is a shorting-plug for altering the efiective mechanicallength and hence the electrical tuning of a, transmission line of the(diplex).type comprising a hollow outer-conductor having a. longitudinalaxis and containing a plurality of inner-conductors arranged in spacedparallelrelation on opposite sides of said axis.

The principal object of the invention is to provide anexpansible-contractible shorting-plug which shall be capableof beinginserted, in its assembled condition, through the open end of a tripleconductor and then moved and clamped, with ease and dispatch, to adesired point in the line-to, provide a low impedanceconnection betweenall three of the said conductors.

The invention will be described in connection with the accompanyingdrawing wherein: Fig. 1 is an end view of a triple conductor containinga shorting-plug constructed in accordance with the principle of theinvention, Fig. 2 is a longitudinal sectional view, taken on the lineII-II of Fig. 1 and, Fig. 3 is a side elevation of the shorting-plug perso.

In Figs. 1 and 2 of the drawing xx designates the inner central axis ofa, so-called diplex transmission line of the type comprising a hollowouter conductor, containing two inner conductors 2 and 3, respectively,which are disposed on opposite sides of the axis xx with their outersurfaces presented in capacitive relation across an intervening space tothe inner surface of the outer conductor, as is required in thesimultaneous transmission of two carrier waves (e. g. television pictureand audio) of very high frequency. The outer conductor i has an open endIa through which access may be had to its interior for the purpose ofinserting the shorting plug P at a desired point in the line.

The supporting element or base of the shorting plug of the presentinvention comprises a metal rod or bar 5 of a length less than thediameter of the outer conductor i and of a width sufliciently narrow tobe received between the inner conductors 2 and 3. The bar 5 serves as acentral support for two complementary yoke pieces 6 and i which,jointly, surround the inner conductors 2 and 3, and also serves as asupport for two arcuate members 8 and 9 which occupy the spaces betweenthe individual yoke pieces and the inner surface of the outer conductor5. ihe yoke pieces 5 and i are supported for relative movement upon thesupporting bar by screws it and II, respectively, which extend throughvertlcally elongated slots l2 and 13, respectively, in

the said bar. The top and bottom arcuate members sand 9, respectively,are similarly supported for relative movement by screws I4 and i5 whichextend, respectively, through elongated slots I6 and I! in the bar 5.

The complementary yoke pieces fi and I serve, in a manner laterdescribed, to exert a clamping force upon the two inner conductors '2and 3, but are normally biased to. their open or unclamped positionbymeans of a coil spring I3, the.

opposite ends of which are seated in holes pro.-.

vided for the purpose in the adjacent faces of the said pieces adjacentto the center of the plug, 1. e, at the rear of the bar 5.

It will be observed upon inspection of Fig. l and 3 that each of thearcuate members Band 9, is connected to the yoke piece which lies adjaecent thereto by a pluraliy of horizontally disposed folded metal stripsIS, 2.9a, 28., 28a, respectively, which are secured along, theiropposite edges to the said members by screws 21 and 22. These foldedstrips l9, Isa, 20, Zea are preferably constituted of phosphor bronze orother springmetal and exert their biasing force in the same direction asthe stronger spring It, i. e. outwardly 0n the arcuate members 8 and 9.The bias pro vided'by the coilspring IB'and the spring metal strips l9,lea, 28, 23a tends to increase the overall diameter of the plug and, asa possible consequence might render it difiicult to insert the plugwithin the outer conductor. The said biasing forces must therefore berestrained and the arcuate members drawn inwardly against said bias asufficient distance to permit the plug to be inserted within the line,by the provision of a compensating mechanism. The compensating mechanismfor each arcuate member comprises a pair 23-2 (25-45) of screw-actuatedcoil springs which are connected through their screws 23s2 ls etc. tothe adjacent yoke piece. It will be observed that access may be had toeach screw from the outer surface of the arcuate member which it servesthrough holes 27 in the said surface. It will also be observed that theweight of the plug is minimized by making the body of the arcuatemembers about the heads of the screws 23s, 248 etc. of hollow oropen-work con struction.

In order to effect the relative inward movement required to clamp theyoke pieces about the inner conductors, and the relative outwardmovement required to urge the arcuate members into engagement with theinner surface of the outer conductor, two metal wedges 2B and 29 areprovided at the rear of the plug where they are accessible foradjustment by two removable rodlike wrenches 30 and 3|. The wedges 23and 29 are mounted, respectively, between the straight surface or chordof each yoke member and the parallel surface of the arcuate member whichlies adjacent thereto, and are received in complementary wedge-shapedseats 32 and 33, respectively, comprising inwardly inclined slotslocated at or adjacent to the center of the said parallel surfaces.

The wedges 28 and 29 are of duplicate construction and are each providedwith a threaded bore containing a screw 34, 35 which extends through aclearance hole 36 (3'!) in the supporting bar 5 at the front of theshorting plug. A cap 34 (35') on the front end of each screw and awasher 38 (39) beneath the said cap permits the screws to be turnedwhile holding them against longitudinal movement. Thus, torque appliedto the rear end of the screws 34 and 35, as by turning the wrenches 30and 3|, will move the wedges 28 and 29 forwardly or rearwardly asdetermined by the direction in whichthe screws are turned. A collar, 60(4 i) on the rear end of each of the screws 34 and 35 contain a bayonetpin 42 (43) for engagement with a complementary bayonet slot in thesocket M (45) of its wrench, thus the wrenches 36 and 3| may be removedfrom the screw collars 4i} and Al when the shorting-plug has beenclamped at a desired point in the transmission line.

It will now be apparent that the present invention provides an improvedshorting-plug and one capable of being inserted, in its assembledcondition, into the open end of a diplex transmission line and thenmoved and clamped with ease and dispatch to a desired point in the lineto provide a low impedance connection among all three conductors of theline.

What is claimed is:

1. A shorting-plug for altering the electrical length of a transmissionline of the type comprising a hollow outer conductor having alongitudinal axis and containing a plurality of inner conductorsarranged in spaced relation parallel to said axis, said devicecomprising: a support of a length less than the inside diameter of saidouter conductor and of a width sufiiciently narrow to be accommodatedbetween said inner conductors, a plurality of complementary yoke piecesmounted for relative movement on said support and adapted to receivesaid inner conductors, a plurality of arcuate members mounted forrelative movement on said support and adapted to extend across said axisin the space between said inner conductors and the inner, surface ofsaid outer conductor, a wedge mounted on said support between each ofsaid yoke pieces and the arcuate member which lies adjacent thereto, andmeans for actuating said wedges whereby to clamp said yoke pieces aboutsaid inner conductors and simultaneously to urge said arcuate membersinto engagement with the inner surface of said outer conductor.

2. The invention as set forth in claim 1 and wherein spring means areprovided between said yoke pieces for biasing said yoke pieces to theiropen position.

3. The invention as set forth in claim 1 and wherein means are providedfor biasing said yoke pieces radially inward toward said longitudinalaxis.

4. The invention as set forth in claim 1 and wherein said yoke piecesand said arcuate members are provided with spaced apart parallelsurfaces and are electrically connected adjacent to said parallelsurfaces by expansible metal inserts mounted between said surfaces.

5. The invention as set forth in claim 1 and wherein saidwedge-actuating means comprises a screw extending through said wedge,said screw being secured at its inner end to said common support andprovided adjacent to its rear end with a bayonet pin for engagement witha complementarily shaped socket wrench.

GEORGE A. KUMPF.

REFERENSES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,203,806 Wolf June 11, 1940

